The Q: "My fiancee has given me the task of searching for transportation for our guests. One option is to utilize the hotel shuttle which holds a max of 15 people. Our other option is to hire a private shuttle service, which could accommodate up to three times as many people (but could be costly). Our problem is that we are not sure how many guests would use a shuttle service. From your experience, what is the proper/easiest way of finding out if our guests would need transportation? We would rather not ask any of our 200+ guests directly. Can you please help me?"
The A: Without being able to ask you any questions, my gut tells me that you should NOT rely on the 15 passenger shuttle, and that 1 40 passenger doing continuous loops would work, but let's try and better assess the situation.
First: it sounds like you have a hotel block for your guests and then you are concerned about getting them to and fro the ceremony/reception site. Common problem, and frankly, nice of you to think about because without the shuttle, even if it's a short distance, you'll have people drinking and driving. The first thing to think about is how great of a demand for that shuttle will there be. Without asking each guest, I would use your hotel pick up list as a guide. That will give you a sense of not only HOW many people will be at the hotel, but also WHO those guests are. (I.e., do you know your friends would all NEED a shuttle, while your aunts and uncles ALWAYS drive).
I would only use the hotel shuttle if I were you if you only have about 15-30 people who might need it. Not knowing the distance between the 2 locations, you could set two times for it to make a loop (let's say 1 an hour prior to start time and the other a 1/2 hour before), but if the "early" shuttle is empty, you might have an over-crowded "late" shuttle, causing some people to be late.
If it looks like you have a mid-sized group of people (like, 30-60) that you think will need the shuttle, you should charter one 40 person shuttle making loops with a schedule leaving every 15 (or whatever the timing is to do a loop) from about 1 hour prior to the start time for ceremony. Print the schedule and put it at the front desk for check in, or in your welcome bags.
On the return, at the end of the night, I think you should have the hotel shuttle loop maybe over the last hour of your reception and then consider if you want to do a larger bus for your guests to head back.
One other thought, if you are still stressed about calculating HOW MANY people will need a new transport is to utilize a "Polling" feature of a wedding website, if you have one. Wedding Window, and a few others, have the ability to take "surveys".
I think the main thing is to give people the option, but also not to give an option that creates MORE confusion: i.e., 20 people trying to rush over to the ceremony in a 15 passenger bus!
Don't get too stressed!